Hi, > How did you test different page sizes. Did you recreate the database over and > over again? > yeep. But I only do this tests when model/data content had important changes or when there are performance problems.
> I use |DB_CLOSE_DELAY=-1 because I want the database to be open when my > server is up > and closed when my server is down. I would assume not closing the database > during the times of inactivity keeps it responsive all the time, right?| Yes , but maybe more risky too. > Would increasing CACHE_SIZE=128000 ever make H2 slower? Yes, I've seen this happen in some cases, but in small measure. > Of course one needs to take care of JVM having enough of memory allocated for > it but other than that > the more you can keep in memory the faster, right? In theory yes, but better to test. Create a non trivial work-load to test, and repeat the tests by increasing the cache size in 16 MB. At some point the increase in performance begins to flatten and then starts to wane a bit. I usually use 80% of value which showed the best result. Allocatememoryin excess, besides not improve performance, leave less memory available for FileSystem's cache at OS level. > Maybe understanding better the practical differences of multithreaded and > mvcc in H2's implementation > would be easier to choose between them. > IMHO multi-thread and MVCC are different animals. Multithread is about in-process contention (thread contention) to do some db tasks in parallel, affecting mainly how H2 will carry out their job internally. >From a user point of view can be perceived as the ability to process >simultaneously more than one user request (query or update). MVCC is a strategy to achieve an usable transaction isolation level with better concurrency (update) than row level locking strategy. It's about contention of access at row or data level for a set of possible operations. >From a user point of view can be perceived as the ability to make readers >don't block on writers. > Now I only assume that MULTI_THREADED works well if you have a lot of > concurrent clients that do mostly reading. yes. regards, Dario -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/h2-database?hl=en.
